Preparation of Cell Wall Antigens of Staphylococcus aureus

Cell walls were prepared from Staphylococcus aureus strains Copenhagen and 263 by high-speed mixing in the presence of glass beads followed by differential centrifugation. Insoluble peptidoglycan complexes were derived from cell walls by extraction of teichoic acid with 10% trichloroacetic acid. Intact teichoic acid was prepared from each strain by digestion of cell walls with lysostaphin and isolated by column chromatography. Soluble glycopeptide (peptidoglycan in which only the glycan has been fragmented) and the stable complex of teichoic acid with glycopeptide were prepared by digestion of cell walls with Chalaropsis B endo-N-acetylmuramidase and were separated by column chromatography. Amino acid and amino sugar contents of walls and subunits of walls were comparable to those reported by others.

Preliminary results on the prediction of countershock success with fibrillation power

In a study of artifact-free ventricular fibrillation episodes in 54 patients, 28 of whom experienced return of spontaneous circulation (ROSC), the power of different indicators to predict the ROSC was compared. Taking the average of sensitivity, specificity and positive and negative predictive value, the dominant frequency reaches 76%, the mean amplitude 72% and fibrillation power 71%. There is little correlation between the three indicators.

In vitro evaluation of antibiotic elution from polymethylmethacrylate (PMMA) and mechanical assessment of antibiotic-PMMA composites

OBJECTIVE

To determine whether different methods of sterilization of antibiotic vials or the heat of polymerization altered the antimicrobial activity or mechanical properties of antibiotic/polymethylmethacrylate (PMMA) composites when compared to antibiotic-free PMMA.

STUDY DESIGN

In vitro study.

METHODS

Steam-sterilized, gas-sterilized, and non-sterilized 1 gram vials of cefazolin and injectable gentamicin sulfate (high and low doses) were mixed with PMMA to prepare composites for antibiotic elution evaluation, compression, and elongation testing. Blocks of PMMA that contained antibiotic were assayed for antibacterial activity using an agar gel diffusion method or were placed in phosphate buffered saline (PBS) to assess elution of antibiotic. Phosphate buffered saline samples from steam-sterilized cefazolin and high-dose gentamicin groups were assayed on days 1, 2, 5, and 9 for cefazolin or gentamicin concentration by high-pressure liquid chromatography or fluorescent polarization immunoassay, respectively.

RESULTS

PMMA blocks containing antibiotic inhibited bacterial growth of Staphylococcus aureus 25923 for an average of 9 days. Cefazolin and gentamicin concentration in PBS decreased dramatically after the first 24 hours, but remained above minimum inhibitory concentration (MIC) throughout the experiment for all groups except low-dose gentamicin. Compressive strength of plugs made from plain cement and plugs made from PMMA mixed with untreated and steam-sterilized cefazolin was similar, but was significantly different from the other groups. There appeared to be an inverse relationship between compressive strength and elongation.

CONCLUSION

PMMA/antibiotic composites inhibited bacterial growth for 7 to 10 days. Compressive strength was affected by different additions of antibiotic.

CLINICAL RELEVANCE

Bacteria introduced during a surgical procedure may be inhibited by elution of antibiotic from PMMA at the time of contamination.

Biodegradable drug delivery systems for gentamicin release and treatment of synovial membrane infection

OBJECTIVE

This study investigated two biodegradable drug delivery systems (BDDS) for elution of gentamicin and elimination of synovial membrane infection.

STUDY DESIGN

The effect of BDDS on control and infected synovial explants was determined.

ANIMALS OR SAMPLE POPULATION

Synovial explants from four adult equine cadavers.

METHODS

First, BDDS were placed in phosphate buffered saline for 14 days. Eluent was tested for gentamicin concentration (G) and bioactivity. Second, synovial explants were divided into four groups (n = 14/group): Group 1 (control); Group 2 (infected control) 405 cfu Staphylococcus aureus added at 6 hours; Group 3 (antibiotic BDDS [Ab-BDDS]) Ab-BDDS added at 24 hours; Group 4 (infected Ab-BDDS) 405 cfu S. aureus added at 6 hours, Ab-BDDS added at 24 hours. Both types of Ab-BDDS were used (n = 7/type/group). Explants were incubated in standard medium for 4 days. Medium was cultured and analyzed for (G) and hyaluronic acid concentration (HA). Explants were analyzed for viability and morphologic changes.

RESULTS

The Ab-BDDS released >500 microg/mL of active gentamicin for 10 days. In Group 3, infection was eliminated within 24 hours, but histologic scores did not return to normal. Viability was significantly reduced by infection, but if eliminated, viability tended to return to normal. In Group 3, the Ab-BDDS had no significant effect on viability or (HA). Histopathologic scores were significantly higher for infected synovium. Infection, even if treated, significantly reduced (HA).

CONCLUSIONS

Both Ab-BDDS eliminated infection within 24 hours. However, synovial morphology, viability and function did not return to normal.

CLINICAL RELEVANCE

The Ab-BDDS may be useful for treatment of synovial membrane infection.

Microbial flora and antimicrobial susceptibility patterns of isolated pathogens from the horizontal ear canal and middle ear in dogs with otitis media

OBJECTIVE

To compare microbial flora and antimicrobial susceptibility patterns of isolated pathogens from the horizontal ear canal and middle ear in dogs with otitis media.

DESIGN

Prospective study.

ANIMALS

23 dogs with chronic bilateral otitis externa.

PROCEDURES

Swab specimens of the horizontal ear canal and middle ear were obtained for cytologic analysis, bacterial culture, and antimicrobial susceptibility testing. Integrity of the tympanic membrane was observed. If the tympanic membrane was intact, myringotomy was performed to collect specimens.

RESULTS

Otitis media was diagnosed in 38 of 46 (82.6%) ears evaluated. The tympanic membrane was intact in 71.1% of the ears with otitis media. The 3 most common organisms isolated from the horizontal ear canal and middle ear were Staphylococcus intermedius, yeast, and Pseudomonas spp. A difference in total isolates or susceptibility patterns between the horizontal ear canal and middle ear was found in 34 (89.5%) ears. Compared with results of bacterial culture, cytologic examination of swab specimens was not as effective for detection of rods and cocci from the middle ear.

CLINICAL IMPLICATIONS

In dogs with chronic otitis externa, otitis media often exists even when there is an intact tympanic membrane. In our study, the same isolates were rarely found in the horizontal ear canal and middle ear. Therefore, to choose appropriate antimicrobial agents, in addition to cytologic examination, bacterial culture and susceptibility testing of swab specimens from the horizontal ear canal and middle ear should be performed.

Survival of Mycobacterium paratuberculosis and preservation of immunoglobulin G in bovine colostrum under experimental conditions simulating pasteurization

OBJECTIVE

To determine whether Mycobacterium paratuberculosis could survive in colostrum after pasteurization. Additionally, this study investigated the effect pasteurization had on IgG concentration in colostrum.

ANIMALS

Colostrum samples were collected from cattle (beef and dairy) owned by the state of Ohio.

PROCEDURE

Colostrum was divided into aliquots and inoculated with variable concentrations of M paratuberculosis (ATCC No. 19698: 10(4), 10(3), and 10(2) colony-forming units/ml). Half the samples at each concentration were subjected to pasteurization temperatures (63 C) for 30 minutes and the remainder were kept at approximately 20 to 23 C. All samples were incubated (Herrold's egg yolk medium with and without mycobactin J) and observed for growth during the next 16 weeks. Additionally, the IgG concentration of colostrum was determined by radioimmunoassay before and after pasteurization. Samples that coagulated at pasteurization temperatures were mechanically resuspended before measurement of IgG concentration.

RESULTS

Growth of M paratuberculosis was retarded but not eliminated by pasteurization. Growth was observed in all unpasteurized samples incubated on Herrold's egg yolk medium with mycobactin J but in only 2 of 18 pasteurized samples similarly cultured. Growth from pasteurized samples appeared 5 to 9 weeks after growth was observed from nonpasteurized samples. Mean colostral IgG concentration was 44.4 g/L in nonpasteurized samples and 37.2 g/L in pasteurized samples, a decrease of 12.3%. High-quality colostrum (> 48 g of IgG/L) had a significantly greater loss of IgG concentration than did colostrum of lesser quality (P = 0.002).

CONCLUSIONS

Pasteurization lessened, but did not eliminate, growth of M paratuberculosis from experimentally inoculated colostrum samples. Pasteurization resulted in a significant decrease in colostral IgG concentration but not to an unmanageable level that would preclude the colostrum's use for passive transfer of immunity.

CLINICAL RELEVANCE

Colostrum is macrophage rich and may serve as a source of M paratuberculosis infection to calves. Pasteurization of colostrum may lessen the risk of infection, but will not totally eliminate M paratuberculosis.

Systemic Mycobacterium smegmatis infection in a dog

A 3-year-old female Basset Hound was examined because of fever and lameness of 2 months' duration. Physical examination revealed a small cranial abdominal mass, which had an ultrasonographic appearance of a large abdominal lymph node. Cytologic examination of an ultrasound-guided fine-needle aspirate of the mass revealed a few macrophages that contained numerous linear unstained structures consistent with mycobacteria. Intracellular acid-fast bacilli were identified in an aspirate that was stained with modified Ziehl-Neelsen. Exploratory laparotomy revealed wide-spread abdominal lymphadenopathy. Histologic examination of hepatic and lymph node biopsy specimens revealed chronic granulomatous hepatitis and lymphadenitis. Acid-fast organisms isolated after bacteriologic culturing of a mesenteric lymph node specimen were identified as Mycobacterium smegmatis. Because the prognosis was poor, the dog was euthanatized.

Pharmacokinetics of single intravenous and single and multiple dose oral administration of rifampin in mares

The disposition of rifampin in six healthy mares after single intravenous (i.v.) and oral (p.o.) doses and after seven oral doses of 10 mg/kg administered twice a day was investigated using a high performance liquid chromatographic (HPLC) method. Pharmacokinetic variables for rifampin determined using the HPLC method were comparable to variables reported from earlier studies utilizing a microbiological assay. Desascetylrifampin, a major metabolite of the parent compound, could not be detected in the serum but was detected at low concentrations in urine. Mean trough concentrations of rifampin increased from the first to the second dose of the multiple dose oral study and then remained unchanged through 72 h. At 84 h after the first dose (i.e. 12 h after the final dose) the rifampin concentration was significantly decreased (P = 0.001). The harmonic mean of the half-life of rifampin decreased significantly from 13.3 h after a single oral dose of 7.99 h after the seventh oral dose. The mean serum protein binding of rifampin over the concentration range of 2-20 micrograms/ml was 78%. Mean trough serum concentrations of unbound rifampin after multiple oral doses ranged from 0.67 micrograms/ml at 24 h to 0.40 micrograms/ml at 72 h. The mean unbound serum rifampin concentration at 84 h (i.e., 12 h after the final dose) was 0.30 micrograms/ml. Trough concentrations and the 84-h sample concentration of unbound rifampin exceeded the minimum inhibitory concentration for most gram positive bacterial isolates from horses reported in this study. All organisms with minimum inhibitory concentrations less than 0.125 micrograms/ml were considered susceptible. Based on the pharmacokinetics of rifampin after p.o. administration, we concur with the current dosage recommendation of 10 mg/kg twice a day by mouth. At this dose, most streptococci, Rhodococcus equi, and coagulase-positive staphylococci would be considered susceptible to rifampin.

Aspergillosis granuloma in the mediastinum of a non-immunocompromised horse

A National Show Horse with a mediastinal granuloma was presented with clinical signs which included fever, nasal discharge and cough. The mediastinal mass was identified radiographically and ultrasonographically. A presumptive diagnosis of aspergillosis was made following isolation of Aspergillus spp. from both transtracheal aspirate and bronchoalveolar lavage fluid samples and agar gel immunodiffusion (AGID) identification of serum antibody to Aspergillus spp. The diagnosis was confirmed by histopathologic examination of the mediastinal mass obtained at necropsy examination.

Prophylactic efficacy of four antibacterial shampoos against Staphylococcus intermedius in dogs

Prophylactic efficacy of 4 antibacterial shampoos against Staphylococcus intermedius in dogs was determined by use of a controlled quantitative technique. Ten adult Beagles were used in the study. The antibacterial agents in the shampoos were 3.0% benzoyl peroxide, 0.5% chlorhexidine acetate, 1.0% available iodine as a polyalkyleneglycol-iodine complex, and a combination of 0.5% triclosan, 2.0% sulfur, and 2.0% salicylic acid. Treated and control sites were challenge exposed with 5.30 +/- 0.10 (log10) S intermedius colony-forming units (CFU)/cm2 of skin and occluded for 5 hours. At the end of the test period, remaining bacteria were removed with a detergent cup-scrub technique and the total number of S intermedius CFU/cm2 skin was calculated for each treated and control site. Nontreated bacteria-challenged control sites yielded 5.62 +/- 0.65 S intermedius CFU/cm2 of skin. Staphylococcus intermedius recovery (CFU/cm2) from the treated sites was 0.94 +/- 0.76 for benzoyl peroxide, 1.96 +/- 1.33 for chlorhexidine acetate, 3.11 +/- 0.48 for organic iodine, and 4.69 +/- 0.23 for triclosan-sulfur-salicylic acid. Each S intermedius recovery value from the 4 treated sites was significantly (P less than 0.05) lower than that from the nontreated S intermedius challenge-exposed control site. Bacteria recovery values were also significantly (P less than 0.05) different among the 4 shampoo-treated sites. We concluded that all shampoos had significant (P less than 0.05) prophylactic activity against S intermedius over 5 hours. The shampoo containing benzoyl peroxide was determined to have the greatest efficacy among the products tested.

Culture-positive persistence and serum agglutinating antibody response after intrauterine inoculation of Haemophilus somnus in virgin heifers

Viable Haemophilus somnus of reproductive tract origin (OSU-1167) was inoculated transcervically into the uterus of 6 virgin heifers. Five heifers were sham-inoculated (intrauterine) with sterile mycoplasmal medium and served as controls. After inoculation and observation, all heifers had nasal and vaginal vestibular swab specimens and serum obtained periodically for 44 days. Signs of systemic illness were not detected. On the day after inoculation, all inoculated heifers had signs of vulvovaginitis, whereas none of the control heifers had similar signs (P less than 0.002). Haemophilus somnus was not isolated from any nasal or vaginal vestibular swab specimens obtained before inoculation or from any nasal swab specimens obtained after inoculation. During the 44 days after inoculation, H somnus was isolated from 25 of 54 vestibular specimens obtained from inoculated heifers and from 3 of 45 specimens obtained from controls (P less than 0.02). Vulvovaginal lesions were associated with vestibular isolation of H somnus in 23 of 25 (92%) such isolations from inoculated heifers; lesions were never associated with concurrent isolation of H somnus in controls. All heifers had H somnus microagglutination test (MAT) titer less than or equal to 256 against a commercially prepared H somnus antigen at the beginning of the study. Considered as groups, neither inoculated nor control heifers achieved fourfold increases in MAT titer during the 44 days after inoculation. When compared by day of sample collection, inoculated heifers did have significantly (P less than 0.04) lower geometric mean titer at 7 days after inoculation than did control heifers when tested by use of a commercially prepared antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

The microbial environment of the ear canal in health and disease

Otitis externa is an important disease of dogs and, to a lesser degree, cats. The yeast Malassezia canis is the most common organism demonstrated in ear infections. Coagulase-positive staphylococci are the most common bacteria isolated, often occurring with M. canis. Pseudomonas aeruginosa and Proteus are gram-negative bacteria that are frequently encountered. Other bacteria, such as beta-hemolytic streptococci, enterococci, Escherichia coli, and Corynebacterium are also important. Malassezia canis, coagulase-positive staphylococci, and Pseudomonas aeruginosa commonly occur as monoinfections, whereas other bacteria are typically associated with mixed infections. Smears may provide rapid diagnosis on which to base empiric treatment. Cultures should be considered in recurrent or refractory cases, especially those involving gram-negative bacteria. In practices that are not equipped to perform culture and susceptibility tests, it is advisable to seek the advice of a microbiology laboratory.

Experimental Pseudomonas aeruginosa ulcerative keratitis model in the dog

Primary Pseudomonas aeruginosa ulcerative keratitis and accompanying secondary ocular disease were induced bilaterally in 12 of 12 dogs subjected to corneal trephination and intrastromal inoculation. Successful experimental infection was based on recovery of viable Pseudomonas organisms from the lesions, as well as gross and biomicroscopic appearance of the corneas.

Effectiveness of educational efforts in implementing mastitis control procedures in commercial dairy herds

One hundred-fifty diarymen in north-eastern Ohio, whose herds had a history of persistently high Wisconsin Mastitis Test scores, were invited to participate in this project, with 43 agreeing to do so. These dairymen were divided into two experimental groups and one control group to determine the effectiveness of two intensities of educational effort on adoption of mastitis control procedures and to demonstrate the effectiveness of mastitis control recommendations. A teat dipping and dry cow therapy program was adopted by more herds in the group with intense educational effort than in the intermediate or control group. Percents of herds in each group utilizing this program in 1977 (start of project), 1978, and 1979 were 8, 75, and 92 for the intense group; 30, 50, and 50 for the intermediate group; and 10, 27, and 27 for the control group. Prevalence of infection declined more rapidly in the intense group with 42, 28, and 24% of cows infected; 39, 25, and 30% in the intermedia, and 56, 35, and 42% in the control group in 1977, 1978, and 1979. Those herds adopting a teat dipping and dry cow therapy program had infection prevalence of 41, 25, and 20% of cows; bulk tank Wisconsin Mastitis Test scores of 15.5, 14.7, and 11.4; and milk production per cow per day of 18.4, 18.4, and 17.5 kg in 1977, 1978, and 1979.

Serum biochemical changes in dogs with experimental Leptospira interrogans serovar icterohaemorrhagiae infection

Inoculation of 2 groups of dogs with 1 X 10(9) and 4 X 10(9) Leptospira interrogans serovar icterohaemorrhagiae produced disease varying from transient fever to uremia and death. Clinical signs of disease in the severely affected dogs were fever, dehydration, depression, and icterus. Laboratory changes in serum of infected dogs included increased urea nitrogen, creatinine, phosphorus, alkaline phosphatase, total bilirubin, aspartate aminotransferase, and alanine aminotransferase. Chloride concentration decreased in the serum of dogs with severe disease. The icterus in the infected dogs did not appear to be related to hemolytic anemia.

Pharmacokinetics and dosage of oxytetracycline in dogs

The pharmacokinetics of oxytetracycline, which was given as a single intravenous dose (5 mg/kg), was studied in normal beagle dogs. Renal function was evaluated by the single injection technique and based on clearance of the radioiodine compounds 125I-iothalamate and 131I-iodohippurate. Values of GFR (4.42+/-0.77 ml/kg/min) and ERPF (12.91+/-1.49 ml/kg/min) showed normal renal function. The disposition curve describing decline of oxytetracycline activity in serum was described mathematically by a triexponential expression. Body clearance was 4.23+/-1.29 ml/kg/min. A dosage regimen (intravenous route of drug administration), based on overall elimincation rate constant (0.1155 h-1) and apparent specific volume of distribution (2 litre/kg), and consisting of a priming dose (10 mg/kg) followed by maintenance doses (7.5 mg/kg) at 12 h intervals was proposed. This dosage regimen was predicted to rapidly achieve and maintain steady state serum concentrations within the range 1.25 to 5.0 microgram/ml, which is therapeutic level for the majority of susceptible microorganisms.

Immunobiological activity of cell wall antigens of Staphylococcus aureus

Guinea pigs sensitized with washed, Formalin-killed cells of Staphylococcus aureus, strains 263 or Copenhagen, were skin-tested with various antigens from these strains including washed viable and heat-killed whole cells, cell walls, the peptidoglycan complexes of the walls, teichoic acid, teichoic acid-peptidoglycan fragments, and peptidoglycan fragments. In nonsensitized control animals, all antigens but teichoic acid elicited acute inflammatory reactions which decreased in size after 10 hr. In animals sensitized with the Copenhagen strain, the reactions to all antigens but teichoic acid and peptidoglycan fragments from either strain remained erythematous and indurated for at least 30 hr and were interpreted as hypersensitivity of the delayed type. Responses in animals sensitized with strain 263 generally resembled those in controls, although in some experiments there was evidence of hypersensitivity.